There is a bug with how the spark TextInput handles 'restrict' property. Highlighted text gets deleted when user tries to enter any character that is not specified in the range of characters for the restrict
Steps to reproduce:
1) Add a spark textinput in a project
2) Set its restrict property to "A-Ba-b" (allow only alpha characters)
3) Run project
4) Enter any numeric character which will normally want be allowed now.
5) Enter any alpha characters
6) Highlight a portion or whole text just entered and hit any numeric character key (0-9) and see that the highlited text will be erased though by not actually replacing that selected text with keystroke input.
A MUST fix rather then enforcing users to find workaround by handling textinput event override.